This paper examines an aspect of the rise of Islamism so far have ignored: “World Muslim Congresses” held immediately following World War II at which delegates discussed the possibility of economic and even political union. For all that scholarship acknowledges that Islamism has some roots in earlier decades, typically it dates the origins of visible Islamist movements to the late 1960s. As such it neglects evidence for a much longer gestation of the Islamist movement that, I argue, reaches back at least to the early Cold War. At a time when colonial governments were dissolving, new states were being established and revolutions were overturning previous regimes, some Muslims were eager to explore the possibilities for cooperation to better protect shared interests in the face of emerging new global realities. At meetings in Karachi, Tehran and Jerusalem they considered how to respond to challenges facing their various countries, and they established organizations to coordinate the promotion of mutual interests. Significantly, these congresses were organized by non-state actors, and they were attended by prominent Muslim intellectuals from dozens of countries. After 1953, this congress movement would be eclipsed by individual states manipulating Islamic organizations for their own interests. It would be more than a decade before Islamism appeared as a transnational force, however already important groundwork had been laid for Muslim cooperation in the context of the increasingly rigid nation-state system. It is no coincidence that among the participants at these early congresses were individuals – such as Sayyid Qutb – who would later become prominent advocates of Islamism. Drawing on the Pakistani press as well as British and French archival materials, this paper documents these congresses and explores the factors that led to their short-lived activity between 1948 and 1953. At this time Muslims faced the very real question of “who speaks for Islam?” Unlike Pan-Islamic efforts to agree on a new Caliphate between the world wars, after 1945, emphasis was upon representatives from Muslim countries transcending national differences to work together to face the challenges ahead. In the 1960s a number of organizations would try to formalize this process, while still later Islamist movements that had emerged in specific national contexts began to organize on a transnational level. Our understanding of these two distinct aspects of international Islam depends in part on recognition that their origins date back to earlier efforts at Muslim unity in the early years of the Cold War.